I try to use it sooner than I would bacon fat though because any "muttony" flavor it might have intensifies as it sits in the fridge, and I like it to be as neutral as possible when cooking stuff in it.

I like using lamb fat to roast potatoes in, on the rare occasions I eat potato. Toss it in with a few sliced leeks, dice the potatoes, season to taste with black pepper, rosemary and sea salt, roast on high until done. Nom and enjoy.

Was going to say fry onions, mushrooms and eggs in it (delicious), but since you have trouble with those, I sometimes use it to fry extra-lean beef mince (it's often cheaper than regular here).

If you continuously end up with way more than you can use, feeding it to your dog will make for the happiest pup you've ever seen! Whenever I fry some my dog won't leave the kitchen for anything. It's the only time she ever sits still :)